Acute effects of alcohol on neural correlates of episodic memory encoding Söderlund, H., Grady, C.L., Easdon, C. & Tulving, E. By Miranda Marchand

The effects of alcohol on on episodic memory have been well established through laboratory memory tasks It has been found that encoding of memories is more affected than retrieval Previous studies have shown that: When compared to a placebo, alcohol reduces cerebral blood flow in task-implicated areas during perceptual processing, simulated driving, verbal fluency and divided attention (Calhoun et al., 2004, Haier et al., 1999, Wendt and Risberg, 2001) Though alcohols effects have been demonstrated through behaviour, no previous studies have identified the neural relations of memory impairment due to alcohol consumption Hypothesized that alcohol would impair memory performance, particularly associative memory due to its effects on the hippocampus Introduction

27 males Prescreened for any neurological, psychiatric or medical disorders Those on any medication, who were left-handed, had not spoken English since age 7 and were outside the year range, were using marijuana on a regular basis or had problematic drinking habits were excluded Accepted participants consumed between 2 and 16 drinks a week No one had drink a on more than 3 separate occasion during a week Experimental and control groups were matched for age, education and initial memory performance Participants

Participants were seen on 2 days Day 1 Participants were given practice trials of the different tasks that would be performed in the scanner Participants were then given their drinks – either placebo or alcohol Participants were placed in the scanner to complete the tasks – this took about an hour Day 2 Participants returned the next day to test their memory for materials presented There was no beverage or scanning in the second day Procedure

Experiments

Experimental condition 18 pairs of line drawings of objects were presented in the experimental condition, each pair was presented twice, each block contained 6 pairs Each pair was presented for 4 seconds, and then a cross-hair was presented for 1 second Participants were asked to decide if there was a meaningful relationship Control condition Pairs of the same line drawing were presented in 5 blocks, 3 pairs per block, 15s long Participants had to indicate which of the drawings was smaller Experiments – Object Pairs

Experimental condition Participants were shown photos of people with a gender appropriate name and were asked to judge whether the name fit the face Shown 5 per block, each pair was shown for 4 seconds followed by a 1 second cross hair Control condition Participants were shown photos labeled either man or woman and they had to determine whether the label was correct or not Shown 3 pairs per block and there was a total of 7 blocks Experiments – Face-Name Pairs

The only region active during both associative and perceptual encoding was an area in the left superior frontal gyrus Regions activated in the placebo group Frontal Cerebellum Parahippocampal gyrus Occipital cortex Precuneus Regions activated in the alcohol group Medial frontal gyrus Results – Object Pair fMRI Data

Main difference between the alcohol and placebo groups was the activation of the right frontal area in the placebo group The left precuneus and and right temporal regions were deactivated in the placebo group, no change in activation was seen in the alcohol group Results –Face-Name fMRI Data

Results – Comparing BOLD responses Hippocampus: Alcohol group showed activation during both conditions Placebo group only showed activation during the semantic condition

What area was activated during all semantic encoding? Placebo group – the left inferior-middle frontal gyrus was activated during all semantic encoding Alcohol group – this prefrontal activation was seen only during the encoding of verbal materials Analysis – Semantic Encoding

1.When performance was not significantly effected by alcohol the group activated the same prefrontal regions as the placebo group 1.Encoding under the influence of alcohol was associated with reduced activity in other encoding related areas 1.The apparent lack of parahippocampal/fusiform activity in the alcohol group was actually due to non-specific activation during both experimental and control conditions The Three Major Findings

Supported behavioural experiment findings with the use of fMRI Was very well laid out The majority of the paper was easy to understand There were a lot of experiments presented in paper The “control” condition was not only used on the control group, made understanding the experiments more complicated Limitations: Only used males Future experiments: use females My Thoughts on the Paper

QUESTIONS?

Calhoun, V.D., Pekar, J.J., Pearlson, G.D. (2004). Alcohol intoxicationeffects on simulated driving: exploring alcohol-dose effects on brain activation using functional MRI. Neuropsychopharmacology 29, 2097–2107. Haier, R.J., Schandler, S.L., MacLachlan, A., Soderling, E., Buchsbaum, M.S., Cohen, M.J., (1999). Alcohol induced changes in regional cerebral glucose metabolic rate during divided attention. Pers. Individ. Dif. 26, 425–439. Söderlund, H., Grady, C.L., Easdon, C. & Tulving, E.(2006). Acute effects of alcohol on neural correlates of episodic memory encoding. Neuroimage, 35, Wendt, P.E., Risberg, J., (2001). Ethanol reduces rCFB activation of left dorsolateral prefrontal cortex during a verbal fluency task. Brain Lang. 77, 197–215. References